Generators & Turbines

Generator Assessment Process – we call it GAP


The life of a generator is mainly dependent on the life of its insulation. Therefore, the aging process of the generator has to be very closely monitored. Just like the pulse rate, the blood pressure, sugar level etc., of a human are indicative of his health condition, the capacitance, leakage current, dissipation factor, polarization index, partial discharge and more factors are indicative of the insulation condition of a large generator.

Estimation of the remaining life of a generator is based on the following information:

  • The life history of the generator
  • A diagnostic evaluation of the generator’s condition
  • The operation mode planned in the future

On an average, the lifetime of the stator and rotor winding of a base loaded generator is about 30 and 20 years respectively. The lifetime will get reduced due to peak load or abnormal operating conditions. Other factors, such as, insulation abrasion, loose end-windings support and contamination may reduce the lifetime expectancy even more.

alfanar Technical Services now offers GAP – a solution to lifetime assessment of large generators – which addresses the problems faced during the lifetime of a generator with an aim of increasing reliability and availability. Moreover, GAP is designed to perform generator assessment linked to the planned outage of the plant and thereby minimizing downtime. GAP is offered in four (4) levels – GAP1, GAP2, GAP3 and GAP4.

The past study and experience have shown that the availability of generator is determined largely by stator winding system, and thereby GAP methodology focus more on the stator winding compared to the rotor, exciter and other parts of the generator.

Just send an e-mail to for more information on GAP

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